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XYLENE POWER LTD.

FAST NEUTRON REACTOR (FNR) SODIUM

By Charles Rhodes, P.Eng., Ph.D.

INTRODUCTION:
Elsewhere on this website Fast Neutron Reactors (FNRs) have been identified as the primary source of energy for meeting mankind's future energy needs. This web page focuses on issues related to the sodium used for FNR primary cooling and secondary heat transport.
 

SODIUM PURITY:
The sodium used as a FNR primary coolant needs to be free of contamination by carbon, calcium, chlorine and nickel. To the extent that these elements are present in the primary sodium over time they will absorb neutrons and become the radio isotopes C-14, Cl-36, Ca-41 and Ni-59 all of which have long half lives and hence are disposal problems. The best strategy is to minimize the C, Cl, Ca and Ni content in the liquid sodium before the reactor is turned on and to the expent possible to further remove these contaminats over time via a side arm filter system.

The cost of reactor grade sodium may be as much as $5.00 per kg. Thus 5000 tonnes could cost as much as $25 million before shipping and handling costs.
 

SODIUM HANDLING:
There should be adjacent liquid sodium storage of sufficient capacity to hold all the primary liquid sodium so as to permit major maintenance/repairs to the FNR primary liquid sodium tank. There must be a means of easily and rapidly transferring heat emitting fuel bundles from the main liquid sodium tank to a spare liquid sodium tank and vice versa.

The sodium will likely be delivered to the site as a solid in open top 55 US gallon steel drums with removeable covers. There may be as many as 25,000 such drums. These drums need to be stored on pallets in groups separated by aisles that act as fire breaks and provide access for fire suppression. A safe drum pallet size is 30 inches X 30 inches. Hence exclusive of aisles the space requirement is:
(30 inches X 30 inches) / drum X 9225 m^3 X 5 drums / m^3 X (.0254 m / inch)^2 = 26,782 m^2

Allowing for aisle area equal to 3 X storage area implies a requirement for 107,128 m^2 = 0.11 km^2 for single layer sodium drum storage.

The drums will likely arrive by rail. Hence the site will need additional area for a rail siding and cargo transfer of:
1 Km X 50 m = .050 Km^2

The FNR needs to have multiple adjacent cooling towers, to provide a secure heat sink. If there is only one dry cooling tower there must be an extremely secure source of cooling water.

The drainage required to ensure dryness of any hill where a FNR is installed below grade will likely have an adverse effect on nearby water wells. The combination of the hill and the cooling towers will be more prominent on the horizon than a cluster of wind turbines of similar height. To avoid problems with neighbours it is recommended that the utility that owns the FNR should purchase all the land within a 0.5 km radius of the FNR. Hence from a simple land acquisition perspective it makes sense to locate several FNRs in a cluster to minimize land acquisition costs. To put this issue in perspective, if the average land area per FNR is 1 km^2 and the cost of land is $50,000 per hectare the minimum cost of the land per FNR is about:
1 km^2 X 100 hectares / km^2 X $50,000 / hectare = $5,000,000
 

This web page last updated January 14, 2018.

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